Final answer:
The possibility of Earth experiencing a magnetic reversal is related to the eleven-year cycles of solar activity and the movement of liquid metal in Earth's outer core. Cosmic radiation does not directly cause magnetic reversals. Option C is correct.
Step-by-step explanation:
The possibility of Earth experiencing a magnetic reversal is related to option c, the eleven-year cycles of solar activity. Astronomers have found that the Sun's changing magnetic field drives solar activity, and this activity can impact Earth's magnetic field. The Sun goes through cycles of increased and decreased magnetic activity every 11 years, and during periods of high solar activity, Earth's magnetic field can become unstable and undergo a reversal.
Additionally, Earth's solid iron inner core being surrounded by a liquid iron outer core, as mentioned in option b, plays a role in Earth's magnetic field. The movement of the liquid metal in the outer core generates electric currents that create the magnetic field.
Option d, the magnetic effects of cosmic radiation, is not directly related to Earth experiencing a magnetic reversal. Cosmic radiation can affect Earth's magnetic field in various ways, but it is not the primary factor contributing to a magnetic reversal.